Method of and apparatus for truing serrated grinding wheels



June 17, 1930. .B. M. w. HANSQN 1,764,043

METHOD OF AND APPARATUS FOR TRUING SERRATED GRINDING WHEELS F iled Dec. 24 1924 I 3 Sheets-Sheet 1 June 17, 1930.

V B. M. W. HANSON METHOD OF AND APPARATUS FOR TRUING SERRATED GRINDING WHEELS s Sheets-Sheet 2 Filed Dec. 24, 1924 r June .17, 1930. B. M, w. HANSON METHOD OF AND APPARATUS FOR TRUING SERRATED GRINDING WHEELS Filed Dec. 24, 924 3 Sheets-Sheet 3' Patented June 17, 1930 UNITED STATES PATENT OFFICE IBENG'I H. W. HANSON, OF HARTFORD, CONNECTICUT; EINAR A. HANSON EXECUTOR OF SAID BENGT M. W. HANSON, DECEASED METHOD OF AND APPARATUS FOR TRUING SERRATED GRINDING WHEELS Application filed December 24, 1924. Serial No. 757,923. 7

The present invention relates to an improved method of and apparatus for truing serrated grinding wheels, such, for instance, as is disclosed in my co-pending applications Serial No. 640,351, filed May 21, 1923, and Serial No. 691,643, filed February 9, 1924. The present application is a divisional, at least in part, of my said application Serial No. 640,351.

The aim of the invention is to provide an improved method of and apparatus for truing serrated inding wheels, the method and apparatus aving various features of novelty and advantage and being particularly characterized by the precision and efliciency'with which the serrations of the wheel may be trued.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

The invention accordingly consists in the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the application of which will be indicated in the appended claims.

In the accompanying drawings, I have shown one form of apparatus which may be employed for carrying out the features of the present invention, it being understood that this showing is by way of illustration only. In the drawings:

Figure 1 is a top plan view showing my improved truin device applied to a grinding machine provi ed with a serrated grinding wheel, the machine being illustrated more or less diagrammatically as the specific construction thereof forms no particular part of the present invention;

Fig. 2 is a diagrammatic view showing a form which the truing device may take;

Fig. 3 is a-top plan view of the truing device of Fig. 1 with parts broken away;

Fig. 4 is a vertical sectional view taken substantially on line J -4 of 'Fig. 3;

Fig. 5 is a detail view, in cross section, of one of the diamond oint slides, this view being taken substantlally on line 5-5 of Fig. 3

Fig. 6 is a detail view parts (if the indexingmcans of the truing device, this view being taken substantially on line 6-6 of Fi 3;

Fig. 7 is a diagrammatic view showing the relative angular positions of the grinding wheel and work when the latter has a thread of large lead to be ground;

Fig. 8is an end view of thearrangement shown in Fig. 7 and additionally indicates the position of the device fdr truing the wheel; and

-Fig. 9 is an elevational view showing an arrangement which permits the angular adjustment of the grinding wheel.

Referring to the drawings in detail, G indicates the grinding wheel and W, a piece of work which may be in the form of a threaded member which has been hardened. The grinding wheel is in the form of a cylindrical member formed of abrasive material, such as carborundum, and having on its periphery a plurality of serrations or cutting edges 10, each of which, by preference, is in the form of a separate continuous ring or rib to the plane of which the axis of the wheel is rpendicular. As pointed outmore in detail in my said than that between adjacent convolutions on the work, in the drawings the serrations being shown as being spaced apart so that they occur at every other groove convolution on the work, it being obvious, however, that the serrations may be. otherwise spaced. As eX- plained hereinafter more in detail in connection with the description of the truing device, which 'forms the subject matter of the present invention, the arrangement of the serrations-on the grinding wheel, in addition to'providing coolingfiuid passages therein,

permits ready and accurate truing of the grinding faces of the serrations.

all

During the rinding operation, a movement is effected between the grinding wheel and work axially of the latter in accordance with the lead of the thread on the work. The extent of this axial movement and other movements of the machine will depend upon the character of the wheel and'the work to be performed. In I my said co-pending application S. No. 691,643, I have shown the serrations of the grinding wheel as being of like shape and size, the machine bein provided with means for repeatedly effecting a back and forth movement between the grinding wheel and work axially of the latter in accordance with the pitch of the thread and through a distance substantially equal to that between adjacent serrationsof the grinding wheel, and means for intermittently effecting a relative feeding movement of the wheel and work towards each other. In the illustrative embodiment disclosed in Figs. 1 and 2 of the accompanying drawings, the serrations of the grinding wheel vary in size or shape so that the serrations will successively grind increments from the successive convolutions of the work, as fully described in my said application 640,351. In the present instance, the

grinding wheel serrations are shown as being of successively increasing width so that thersuccessive serrations will progressively grind small increments from the sides of the grooves of the threaded member, it being understood, however, that this showing is by wag of exemplification only.

the present 1nstance,-the machine is shown as having a base 12 upon which is mounted for transverse adjustment a slide 13 provided with an upstanding bracket 14. Adjustable on this bracket is a bearing box 15 in-which is rotatably supported a grinding wheel shaft 16. 17 is a work support or a slide-upon which is mounted head and tail stocks 18-and 19, the head stock being provided with a splined spindle 21. In theselected illustrative disclosure, during the grinding operation, the grinding wheel is rapidly rotated, as by means of a belt (not shown) passing about a pulley 22,- and the work is slowly rotated by the driven spindle 21 and is axially moved, as by means of a lead screw 23, the relative motions of the work being so proportioned that the serrations provided on the periphery of the rinding wheel will form or finish the thread or threads of the work to the desired lead. The work spindie 21 and the lead screw '23 may be driven one from the other, as through suitable change gears 24. The (grinding wheel slide 13 may be moved towar s and away from the work in any suitable manner, as b means of a screw 25 provided with a ban wheel 26. If desired, the screw 25 may be provided with a micrometer 27 by means of. which fine adjustm'ent'in positioning of the wheel may be had.

Referring now more particularly to my improved truing mechanism, and particularly to Figs. 1, 3, 4, 5, and 6,30 indicates a slide mounted on a support 31 for movement back and forth longitudinally of the grinding wheel. By preference, the truing device is pivotally supported in order that it may be thrown out of the way when not in use and to this end the support 31 is fixed to a shaft 32 journalled in suitable bearings 33 arising from the base. At the ends of the shaft 32 are anti-friction thrust bearings which may be in the form of balls 34. Engaging against one of these balls is a plunger 35 behind, which is a spring 36 housed within one end of the shaft 32. 37 is an adjusting screw threaded into a fixed sleeve 38 and bearing against the ball 34 at the other end of the shaft. It is noted that the spring 36 maintains the shaft a ainst the screw 37., o By turning the screw 3 the truing. device,-as"a-whole, may be very accurately adjusted vso as to bring the diamond pointsintoproper relation to the serrations of the wheel-.I The slide; 30 may be clamped in any positionofadjustment by a bolt 40 having, on its forward end, a bushing 41 adapted to be forced against a guard 42 carried by the slide 30. Mounted on the slide 30, for movement on lines which are parallel to ,the respective side faces of the serrations of the grinding wheel tobe trued, are slides 45 and 46 which carry, at their forward ends,

diamond point holders 47 and 48, respectively, in the outer ends of which are diamond points 49 and 50, respectively. The holders 47 and 48 are at an angle to the lines on which the slides 45 and 46 aremoved so that the diamond points may be brought to properly operate on the side faces of the serratlons. The slides 45 and 46 are guided by ways 51 and may be provided, at each side,

with dust guards 52, as shown most clearly in Fig. 5. For the purpose of limiting the extent of movement of the slides and the diamond points carried thereby towards the wheel, each of the slides is provided with a set screw 53 adapted to engage the rear'end of the respective way 51. The diamond point slides may be longitudinally reciprocated so as to move. the respective diamond points back and forth across the faces'of the serrations in any suitable manner, as, for instance, by means of a lever 54 pivoted to the main slide 30, as at: 55, and having a bifurcated end 56 adapted to straddle pins 57 carried by the diamond oint slides.

The truing means, including the diamond points, are indexed relatively to the grindmg wheel so that they may successively operate on the serrations and, to this end, the following arrangement ma be provided. 601s a lead screw journalle inv the support 31 and havlng threaded engagement with the slide 30. On the outer end of this screw, is

a handle 61' by ineans oflswhich it may be rotated. Fixed to the screw is a pinion 62 meshing with a gear 63 fixed to the hub of a disk 64 journalled on a stud 65. This stud has a rectangular portion 66 engaging in a horizontally extending slot 67 in a part of the support 31. The stud is clamped in adjusted position in the slot by a nut 68. Fixed to the outer end of the stud and against rotation relative thereto is an arm 69 provided with a spring pressed plunger 70, the outer end of which is provided with a handle or knob and the inner end of which is adapted to be engaged in a notch or slot 71 in the disk 64.

\Vhen it is desired to true a grinding wheel having serrations of like size and shape, as shown in Figs. 3 and 7 the truing device is thrown over to the operative position, and the grinding wheel is advanced into operative relation to the truing device, as by turning the hand wheel 26. A gear 63 of such size will be selected that when it is rotated by the pinion 62 one complete revolution, the

. slide 30 will move a distance corresponding to that between adjacent serrations on the grinding wheel. It will be understood that a number of interchangeable gears 63 varyingin size from one another will be provided, and that, by selecting the proper gear, the truing device will be indexed upon each complete revolution of the disk 64 through a distance equalthatb'tween adjacent serrations of the particular wheel to be trued.

The support 31, together with the parts carried thereby, may be adjusted longitudinally of the wheel, in 'order that the diamond points are in proper relation to the serrations, by turning the screw 37. After the truing device has been properly set up, the slide 30 may be brought to a position where the diamond point will operate upon a serration of the grinding wheel and, in this position, the plunger 70 will engage in the notch 71 of the disk 64. The diamond point 50 will be moved back and forth by rocking the free end of the handle 54 so as to true the left hand face of the serration with which the diamond point cooperates. The plunger 70 is then drawn out and the screw is turned, and when the diamond point has been brought into proper indexed relation to the next serration, the'plunger will spring into the slot or notch7 1. The diamond point is now moved back and forth across the left hand face of the second'serration by rocking the handle 54. The diamond point 50 is thus indexed to. successive positions and moved back and forth across the corresponding side faces of the several serrations until these side faces are properly trued. Then the diamond point 49 will be brought into proper relation to true the right hand face of one of the serrations. The handle 54 will be reversed so that thebifurcated end thereof straddles the pin 57 of the slide 45. The handle will be rocked back and forth so that the diamond point 49 will be" moved across the right hand face of the serration. The

diamond point 49 is successively indexed so as to operate upon the several serrations in the same manner as was the diamond point 50. After the wheel has been trued, the

truing mechanism may be swung out of the way, and the grindiiig wheel may be moved in position to operate on the work Without changing the axial relation of the wheel and the work holder. j

\Vhen the truing mechanism is employed for shaping or retrning the stepped serrated wheel, as shown in Fig. 1, the diamond points are indexed longitudinally of the Wheel and are moved back and forth in each indexed position so asto resurface the respective grinding surfaces in the same manner as in the preceding embodiment, except 'that the grinding wheel is moved radially, as by turning the hand wheel 26, a very slight distance each time the diamond points are indexed so that the serrations will be of increasing diameter, which means that they will be of successively increasing widths at equal distances from the axis of the wheel. The positioning of the wheel may be determined by the scale or micrometer 27 More specifically, assuming that the diamond points 49 and 50 have retrued the respective faces of the first serration 10, the truing device will be indexed then be moved back and forth to true the faces of the third serration 10. This sequence of steps may be repeated until the side faces of all of the serrations are properly trued. The serrations will now have all the same pointed shape. but will be of increasingly larger diameters. The wheel may be used in this condition to grind V threads. Preferably, the final serration 10 will correspond exactly in cross section to the size and shape whichv it is def siredto give to the finished thread groove. The serrations may be brought to the same diameter by truncating the same (with the exception of the final serration) and this may be done by moving the slide 30 lengthwise of the wheel with one of the diamond points adjusted to'cut off the points of the grinding serrations. It will be understood that, since the disk 64 has but one notch, this disk will make one complete rotation upon each indexing movement, which means that the slide 30 will be moved exactly the same extent each time it is indexed.- Of course, the serrations may be so truncated that they are of progressively increasing height.

Cal

The truing device is shown, more or less diagrammatically, in Fig. 2. The parts of this truing device which correspond to those just described hear corresponding reference numerals, except that the same are primed. 'lhe micrometer or scale 75 may be employed for properly indexing the diamond points. The slides 45 and 46' may be moved back and forth by turning screws 76. The truing device, in this figure, is illustrated as having a central slide 77 carrying a diamond point or cutting tool 78 which may be employed for roughing out the grooves in the wheel or for truncating the serrations. The serrations may be made of increasingly greater widths in the same-manner as in the preceding embodiment; that is, by positioning the wheel 1 at successive distances from the truing device or, if desired, the wheel may remain stationary and each time the slide 30 is indexed, it may be moved a distance corresponding to the desired distance between adjacent serrations plus (or minus, as the case may be) one-half of the difference between the desired widths of adjacent serrations.

It is of importance to note that, since the grooves in the grinding wheel are substantially deeper than the extent to which the serrations project into the work during the grinding operation. it-is necessary to true the side faces of the serrations for a portion of their depths only, and thus a more precise and accurate form of serration can be conveniently obtained, particularly so since it is not necessary to accurately shape the bottom of the grooves of the grinding wheel. \Vhere the serrations are spaced apart so as to grind non-adjacent convolutions of the thread groove, there is sufiicient space between the convolutions to accommodate the diamond oints, a feature which is of considerable,

' during the grinding operation, but it allows q wheel were placed parallel,

a closer scrutiny of the action of the diamond points upon the serrations during the truing process.

'lVhen it is desired to grind a thread of large lead angle, such as shown in Fig. '2, the

axis of the grinding wheel is inclined er-' penolicularly to the lead of the thread at the work. In this position, the serrations of the grinding wheel extend substantially in the direction of the thread angle of the work in stead of across the thread, as would. be the case if the of the work and grin rig to anus c at the serrav the B 'L st the wi'ieel s angnlarly ad tions are in; of the thread, jOlll'llitl hos; it

.. the

arcuate shape, the center of curvature of the bracket being preferably at a point 85, by which is meant a point in the axis of the wheel substantially mid-way between its ends. The serrations are so shaped and trued that at the point or line at which they engage the work, they will be of such contour and size as to properly and respectively operate on those portions or faces of the t read, as has been planned. In the-present illustrative disclosure, the diamond points are moved in a plane includin the axis of rotation of the work and the point 85; in other words, they move in a practical grinding plane which substantially includes the axis of the, work and the line of contact between the work and the wheel so that the serrations on the grinding wheel are trued to the desired size and shape. It is true that, with the arrangement shown in Figs. 7 8 and 9, one end serration will engage the work slightly above the point of engagement between the central serration and the Work, while the other end serration will engage the workslightly below the last mentioned point, but, for all practical purposes, this deviation is, ne ligible, and the grinding plane may be considered as sub stantially includingthe axis of the work and the point of contact between the work and the several serrations or, at least, a mean of those points.

As many changes cbuld be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all mat ter contained in the above description or shown in the accompanying drawing shall beinterpreted as illustrative and not in a limiting sense.

It is also to be understood that the language used in the following claims is intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

l claim'as my invention:

1. The methodof shaping or truing an abrasive wheel having a plurality of Serra} tions with angularly arranged side faces,v which consists in rotating the grind wheel, indexing in unison a pair of diamon points for operation on respective faces 013"" clined correspondingl diamond points thereacross throu h a distance less than the depth of said aces.

3; The method of shaping or truing a grinding wheel having a plurality of concentric serrations for cutting threads and the like, which consists in angularly adjusting said wheel so that the serrations are inclined correspondingly to the lead of the' thread to be ground, and then truing said serrations in a practical grinding plane.

4. The method of shaping or truing a grinding wheel having a plurality of concentric serrations for cutting threads, which consists in truing said serrations substantially on a line angularl disposed to the axis of the wheel in accor ance with the angular disposition of the axis of'the wheel and the axis of the work when the serrations are into the thread angle of the work by indexing a pair of diamond points on said line for operation on successive serrations of the wheel and moving the diamond points back and forth across the respective faces of a serration in each indexed position.

5. Mechanism for truing serrated grinding wheels, including non-rotatable tool means for truing the serrations of the wheel, means for indexing said tool means for operation upon the several serrations of the wheel, means for guidin said tool means rectilinearly and means or moving said tool means rectilinearly back and forth across the faces of a serration in each indexed position.

6. Mechanism for truing serrated grinding wheels, including a slide movable generally longitudinally of the wheel to be trued, a pair of diamond points mounted on said slide for v rectilinear movement-in accordance with the respective faces of the serratlons, means for indexing said slide and diamond points thereon so that the latter may operate upon the several serrations of the wheel, and means for rectilinearly movmg the diamond points back and forth towards and away from the axis of the wheel in each indexed position of said slide.

7. Mechanism for truing serrated grinding wh eels and including a support, a slide mounted thereon for movement generally longitudinally of the wheel, diamond points mounted on said slide for movement in accordance with the angularity of the respective faces of the serrations, means for indexing said slide and the diamond points thereon generally longitudinally of the wheel, and means for adjusting said support in the direction in which said slide is indexed.

8. Mechanism for truing serrated grinding wheels and including an adjustable support, a slide mounted thereon for indexible movement generally longitudinally of the wheel,

diamond points carried by said slide for movement inaccordance with the angularity of the respective faces of the serrations, means on said support for indexing said slide, and

means for adjusting said suport andthe parts tions, means for moving-said diamond points back and forthin each indexed position, and means for indexing said slide, said indexing means including a rotatable member operatively connected to said slide, a disk driven in timed relation by said rotatable member, and means cooperating with said. disk each time it is operated to limit rotation thereof to one complete revolution.

10. Mechanism for truing serrated grinding wheels and including a slide indexible generally longitudinally of the wheel, diamond points mounted thereon for movement in accordance with the respective faces of the serrations, means for moving said diamond points back and forth in each indexed position, and means for indexing said slide, said indexing means including a rotatable screw the angularity of the respective side faces of the serrations, means for indexing said dia- 'mond point slides. a diamond point holder mounted on each slide, and a diamond point at the end of each holder, said holders extending laterally of said slides.

12. In combination, means for rotatably supporting a serrated grinding wheel, a pair of diamond points mounted for movement at an angle to each other in accordance with the side faces of the serrations of the wheel, means for effecting an indexing movement between the diamond points and grinding wheel support, means for moving said diamond points back and forth in each indexed position, and means for efl'ecting a movement of the wheel support and diamond points generally radially of said support.

13. In combination, means for rotatably supporting a piece of work, a grinding wheel having a plurality of serrations on its periphery, means for adjusting said wheel angularly in relation to the axis of said work supporting means, a pair of diamond points, means for indexing said diamond points on a line angularly disposed to the axis of the wheel in the relation to which the axis of the wheel is "Mil inclined to the axis of the work during the grinding o eration, and means for moving the diamon points back and forth across the respective faces of a serration in each indexed position.

14. Mechanism for truing' serrated grimling wheels and including a pairof slides mounted for movement at an angle to one another and in accordance with the angularity of the respective side faces of the serrations, means for moving said slides, a diamond point holder mounted in each slide and extending laterally and forwardly thereof, and a diamond point at the end of each holder and extending laterally and forwardly thereof. BENGT M. W. HANSON. 

